Aero chamber rosette



May 1s, 1943. F, c, EVANS ETAL 2,319,671

' AERO CHAMBER RosETTE FiledDec. 7, 1938 FIG. l

y. ALM/ZL y ATTORNEY ,ing alarm signals.

Patented May 18, 1943 AERO CHAMBER RosE'rTE Francis C. Evans, Dongan Hills, Staten Island,

N. Y., and Frank M. Cowan, Plainfield, N. J., assignors to American District Telegraph Company, New York, N. Y., a corporation of New Jersey Application December 7, 1938, Serial No. 244,394

4 Claims. (Cl. 177-355) This invention relates generally to re direction systems of the type employing aero tube circuits which respond to a predetermined rate of rise of temperature within an enclosure and thereby detect dangerous changes of temperature or fire conditions. The invention relates more particularly to a heat detector unit for use in and as a part of an aero tube circuit of the type described above and adapted to protect localized areas suph as closets, small rooms, 'cabins in ships, or special areas within a large enclosure.

Within large enclosures the best form of re detector system is believed to be the aero tube system but in iire protection of small spaces, such as closets or cabins and the like, the use of aero tubing becomes diiicult and involves considerable expense. The reason for this is that aero tubing operates on a given rate ofV rise of temperature and creates pressure impulses under those conditions which may be used in generat- Furthermore, a minimum length of tubing is necessary to produce a sufficiently large pressure impulse at the desired rate of rise of temperature and this necessitates the use of 25 to 45 feet of tubing within a small room such as a closet where the volume of air few which is heated inthe event of a fire issmall and confined to such a room. In some cases it is impossible to use such great lengths of tubing and in most cases it is not economically feasible to devote the vnecessary tubing to such small spaces. In prior practice rosettes have been constructed of aero tubing in the form of small loops concentrated within a small space and having v the minimum required length of tubing. These rosettes, however, are bulky and expensive to manufacture and therefore a cheaper and more 'eiicient form of rosette is desirable.

In developing a new form of rosette it is necessary that the characteristics of an aero tube circuit be preserved. Therefore it is necessary that an equivalent device must be capable of generat- -ing a pressure impulse at a given rate of rise of temperature. It must be connected in a regulation aero tube circuit and leaks either in the rosette or in the aero tube circuit must not disable the protection system.

y'circuit I 1.

given length of aero tubing when it is desired to protect small enclosures such as closets, cabins in ships, or other small rooms.

Another object of this invention is to provide a heat detecting rosette which is the vfull equivalent in every respect of a given length of aero tubing.

Still another object of this invention isto provide a heat detector unit for use in aero tube circuits which will not disable the aero tube circuits when leaks develop either in the detector unit or some other part of the aero tube circuit.

Y A further object of this invention is to provide a heat detector unit for use in aero tube circuits and capable of collecting heat eciently and generating a pressure impulse for transmission to an aero tube circuit upon the occurrence of a predetermined rate of rise in temperature.

Further objects and advantages of this invention will be apparent to those skilled inthe art after consideration of the following description and drawing wherein:

Fig. 1 -is a side elevational view of a vheat detector unit constructed in accordance with this invention;

Fig. 2 is a plan view taken on line 2-2 of Fig. 1; A

Fig. 3 is a cross-section of Fig. 2 taken on line 3 3; and

Fig. 4 is a side elevational view of a modication of the detector unit shown in Fig. 1.

Fig. lof the drawing shows a heat detector unitv or rosette fastened in its operative relation to a wall or ceiling of a small enclosure such as a rooml or closet and as an element of an aero tube The unit is made up of a base member I having the studs 3 attached thereto for the purpose of supporting the unit from the ceiling. The base I has spacing elements 4 thereon for the purpose of spacing the unit from the supporting wall or ceiling to allow suicient circulation of air within the base member and to allow ingress and egress of the aero tube I8. Supported on base I is a hollowv can member 6 which en- --closes a smallquantity of air, this quantity being equal to that within 25 to 45 feet of aero tubing.

vThe air chamber 9 within can 6 mustv detect temperature variations in an efficient manner and for The can member I is closed by a cover III ,which is sealed and clamped by a. sealing ring 55 I I and a clamping ring I 2. The supporting rings I4 are placed within the clamping ring I2 for the purpose of adequately distributing pressure from the clamping member I2 to the sealing ring II and cover I0. The aero tubing I8 enters the air chamber 9 through cover Il) and is supported by the tubing holders I5. The tubing holders have a restricted air passage IS therein smaller than the bore of tubing I3 for allowing passage of air from chamber 9 to the tubing I3.

As explained above the detector unit or rosette must have the characteristics of an areo tube circuit, the principal one being that it must respond to a rate of rise in temperature. The aero tube circuit itself is vented at I9 to allow dissipation or equalization of pressure within the tubing resulting from ordinary ambient or slow changes in temperature and since the rosette is an integral part of the aero tube circuit, it also responds to a given rate of rise in temperature" by a corresponding rise in pressure of the gas confined therein. Another important characteristic of aero tube circuits is that a leak in the tubing does not entirely prevent operation. The tubing is roughened onthe inside surface in such a manner that pressure pulses are resisted to a certain extent whereby if a leak occurs in a given section of the tube a pressure pulse will still reach the detector unit through or grill.

the parallel arm of the loop of tubing and close the contacts 2i) Within an alarm circuit. The rosette is provided with restricted passages I6 for connecting the expansion chamber 9 with the tubing I8, these passages serving to delay pressure impulses in the same manner as an equivalent length of aero tubing since they are smaller in diameter than the bore of said tubing. Thus, if a leak occurs in the can 6 or anywhere else in the detector unit, the undamaged section of aero tube connecting to either side of the rosette can still respond to given rates of rise of temperature.

Fig. 4 shows another modification of the rosette which is very similar to that described above. It is provided with a base 2| which supports a spider 22 and guides 21. The guides and spider support a bellows 23 which serves to collect heat and change the pressure within the aero tubing I8. The tubing holders I5 in this unit are lsimilar in construction to those vshown in Fig. 3 and also give the same results. The

stop 25serves the purpose of preventing the bellows from expanding and therefore allowing pressure to build up Within l the bellows upon the occurrence of temperature variations. The operation of this embodiment of the invention gives practically the same results as that shown in the previously described gures of the drawing, but

it is more expensive and complicated to manu-A facture.

From the above description of the drawing, it is evident that the objects of the invention have been fulfilled. The detector unit as a whole has been reduced to its simplest form and is inherplete aero tubing circuit. Because of these characteristics, the rosette is particularly adapted to its intended purpose. It can be installed within small enclosures such as closets, cabins of ships, or other small rooms Within a building. It is even useful YWhere it is not convenient to run tubing into the enclosure which it is desired to protect. For instance, a closet or cabin may have a door which is provided with a transom In this case the rosette may be installed close to the grill or transom and in the path of air coming through the grill or transom so that in the event of dangerous rises in temperature within the closet or cabin, the hot air expelled therefrom will cause operation of the aero tube circuit.

It is not intended that this invention shall be limited to the particular embodiments shown and described above since many others will occur to those skilled in the art and we desire that the invention shall be limited only to the extent of the prior art and the appended claims.

We claim:

1. In combination, an aero tube protective circuit adapted to detect abrupt changes of temperature within an enclosure and a detector unit connected in said aero tube circuit for detecting temperature changes within a given area comprising a heat collecting means comprising an expansion chamber and means providing a normally open restricted connection between said tubing circuit and said chamber whereby the passage of air from said tubing to said chamber is s-uiciently delayed to maintain said tubing operative during temperature changes and in spite of a leak in said chamber.

2. In combination, an aero tube protective cir, cuit adapted to detect changes of temperature within an enclosure and a detector unit connected in series relation with adjacent ends of the tubing of said aero tube circuit for detecting changes of temperature within a given area comprising means for dening a heat collecting expansion chamber and means defining normally open restricted passages for connecting said adjacent ends of said aero tube circuit to said expansion chamber and delaying the transmission of pressure impulses between the tube circuitvand the chamber whereby a leak in'said expansion chamber cannot render said tubing inoperative.

3. A heat detector unit for use in an areo tub'e circuit comprising means for defining an expansion! chamber adapted to collect heat and detect changes in temperature and tubing holders supported on said means within said expansion chamber and having normally open restricted passages therein for connecting an aero tube to said chamber, said restrictedpa'ssag'es delaying the transmission of pressure changes between the Vtube circuit Yand the expansion chamber.

-ber and defining a'normally open restricted passage for restricting the passage of air to delay the transmission of pressure between said chamber and said tube whereby said detector'unit simulates a given length of aero tube circuit.

FRANCIS c. EVANS. FRANK M` c'owAN, l 

